A high-strength optical fiber and a method for manufacturing the same

Abstract

This invention discloses a high-strength optical fiber and its preparation method, comprising a glass portion and a coating portion; the glass portion is a single-mode, multimode, or special optical fiber type; the coating portion uses a resin material, specifically including an inner coating and an outer coating; the outer coating is doped with carbon nanotubes at a mass fraction of 0.3%~5%, and the carbon nanotubes are uniformly distributed along the optical fiber axis in the outer coating; the carbon nanotubes prepared by this invention are uniformly distributed along the optical fiber axis in the resin. Due to the extremely high aspect ratio and superior mechanical properties of carbon nanotubes, the tensile strength of the optical fiber is greatly improved, and increases with the increase of carbon nanotube content in the coating. At this time, the tensile strength of the high-strength optical fiber tested at a strain rate of 5% / min shows that the stress values ​​with a 15% failure probability and the stress values ​​with a 50% failure probability are both ≥6GPa.

Description

Technical Field

[0001] This invention belongs to the field of special optical fiber manufacturing technology, specifically relating to a high-strength optical fiber and its preparation method. Background Technology

[0002] The structure of conventional optical fiber consists of a glass portion and a coating. Since the modulus of the coating portion is generally several hundred to several thousand MPa, which is much lower than the modulus level of about 70 GPa of quartz glass, the tensile strength of optical fiber mainly depends on the glass portion. The theoretical tensile strength of a bare optical fiber with a cladding diameter of 125 μm exceeds 15 GPa. However, due to microscopic defects on the quartz surface and environmental influences, the actual strength will be greatly reduced. The strength of conventional optical fiber is about 5 GPa. During the use of optical fiber, as water molecules erode the surface of the optical fiber, microcracks gradually expand, and the strength of the optical fiber will further decrease.

[0003] Currently, the main way to improve the tensile strength of optical fibers is by adding a protective layer to the outside of the fiber, which is called cabling. However, the cabling process significantly increases the size and weight of the optical fiber, which cannot meet the needs of various miniaturized applications. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a high-strength optical fiber and its fabrication method, which meets the requirements of various miniaturization applications while possessing high strength.

[0005] To achieve the above objectives, the following technical solution is adopted: A high-strength optical fiber includes a glass portion and a coating portion; the glass portion is a single-mode, multimode, or special optical fiber type; the coating portion is made of resin material, specifically including an inner coating and an outer coating; the outer coating is doped with carbon nanotubes at a mass fraction of 0.3% to 5%, and the carbon nanotubes are uniformly distributed along the optical fiber axis in the outer coating.

[0006] According to the above scheme, the diameter of the glass portion is 123μm~127μm.

[0007] According to the above scheme, the resin material is acrylate, the inner coating has a Young's modulus of 0.1~10MPa and an inner coating diameter of 180μm~200μm, the outer coating has a Young's modulus of 500MPa~1000MPa and an outer coating diameter of 230μm~260μm.

[0008] According to the above scheme, the resin material is polyimide, the inner coating has a Young's modulus of 1 GPa to 2 GPa and an inner coating diameter of 135 μm to 145 μm, the outer coating has a Young's modulus of 2 GPa to 4 GPa and an outer coating diameter of 150 μm to 160 μm.

[0009] According to the above scheme, the aspect ratio of the carbon nanotubes is above 1000:1.

[0010] According to the above scheme, the high-strength optical fiber is tested for tensile strength at a strain rate of 5% / min, and the stress value with a 15% failure probability and a 50% failure probability are both ≥6GPa.

[0011] This invention also provides a method for preparing the above-mentioned high-strength optical fiber, comprising the following steps: (1) Prepare an acrylate or polyimide optical fiber coating slurry as an inner coating slurry; mix the modified carbon nanotubes with positively charged outer surfaces and silane coupling agent with the optical fiber coating slurry, and disperse them uniformly as an outer coating slurry; (2) The preform is drawn into a bare optical fiber in a drawing furnace. After cooling, it passes through a first-stage coating cup to coat the surface of the bare optical fiber with the inner coating slurry. After UV curing or thermal curing, the inner coating is formed. (3) The optical fiber with the inner coating is passed through the second coating cup. A ring coil is provided around the second coating cup. Current is passed through the coil to generate an induced magnetic field. The modified carbon nanotubes in the outer coating slurry are arranged along the optical fiber axis under the action of Coulomb force. After ultraviolet curing or thermal curing, the outer coating is formed.

[0012] According to the above scheme, the modified carbon nanotubes with positive charges on the outer surface mentioned in step (1) are aminated carbon nanotubes, which are protonated under acidic or neutral conditions to form -NH3. + This makes the carbon nanotubes positively charged.

[0013] According to the above scheme, the optical fiber coating slurry in step (1) is made of acrylic resin; in step (2), the first-stage coating cup feeding system is controlled within a temperature range of 30℃~50℃, and the viscosity of the inner coating slurry is maintained at 1000~2000cps; in step (3), the second-stage coating cup feeding system is controlled within a temperature range of 40~60℃, and the viscosity of the outer coating slurry is maintained at 500~1000cps.

[0014] According to the above scheme, the optical fiber coating slurry in step (1) is made of polyimide resin; in step (2), the first-stage coating cup feeding system is controlled at a temperature range of 20~40℃, and the viscosity of the inner coating slurry is maintained at 1000~2500cps; in step (3), the second-stage coating cup feeding system is controlled at a temperature range of 20~40℃, and the viscosity of the outer coating slurry is maintained at 1000~2500cps.

[0015] When the carbon nanotube doping content is ≥2%, it will have a strong absorption effect on ultraviolet light, which will affect the curing effect of the coating. It is preferred to use heating for curing, otherwise ultraviolet curing is chosen to increase the drawing speed. Finally, the optical fiber is wound onto the take-up spool by the take-up device.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: In this invention, carbon nanotubes are uniformly distributed along the optical fiber axis in the resin. Due to the extremely high aspect ratio and superior mechanical properties of carbon nanotubes, the tensile strength of the optical fiber is greatly improved, and it increases with the increase of carbon nanotube content in the coating. At this time, the tensile strength of the high-strength optical fiber tested at a strain rate of 5% / min, the stress value with a 15% failure probability and the stress value with a 50% failure probability are both ≥6GPa. Attached Figure Description

[0017] Figure 1 : Schematic diagram of the apparatus for preparing high-strength optical fiber according to the present invention.

[0018] Figure 2 : Schematic diagram of the second-stage coating cup device of the present invention.

[0019] Among them, 1-optical fiber, 2-first-stage coating cup, 3-first-layer two-stage curing, 4-second-stage coating cup, 5-second-layer two-stage curing, 6-drawing furnace, 7-preform, 8-coated body, 9-induction coil, 10-water (temperature-controlled water bath), 11-coating, 12-coating mold. Detailed Implementation

[0020] The following embodiments further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0021] In the specific implementation, the acrylic fiber coating paste used is YP056 and YS006 coatings produced by Puli Technology Qianjiang Co., Ltd., where YP056 is the inner coating and YS006 is the outer coating.

[0022] In the specific implementation, the polyimide optical fiber coating paste used is PI2525 paste produced by DuPont.

[0023] In this specific embodiment, the carbon nanotube raw material used is commercially available carbon nanotube powder, meeting the requirements of a tube diameter of approximately 10 nm, a length ≥ 10 μm, and a purity ≥ 99.9%. 1 g of carbon nanotube powder is added to 100 mL of strong acid (concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1), ultrasonically dispersed for approximately 20 min, and stirred in a 60°C water bath for 2 h. The stirred solution is then filtered through a 0.45 μm polytetrafluoroethylene filter membrane, repeatedly washed with deionized water until the filtrate pH=7, and vacuum dried at 60°C for 24 h. This step is used to introduce carboxyl groups at both ends. Then, 0.5 g of carboxylated carbon nanotubes are dispersed in 100 mL of deionized water, and 1 g of EDC is added. The carboxyl groups were activated with HCl and 0.6g NHS for 30 min, then 2g ethylenediamine was added, and the mixture was stirred at room temperature for 12 h. The mixture was then filtered, washed, and dried for 24 h to obtain aminated carbon nanotubes.

[0024] A specific embodiment provides a method for fabricating high-strength optical fibers, as shown in the attached figure. Figure 1 and attached Figure 2 As shown: (1) Prepare an acrylate or polyimide optical fiber coating slurry as an inner coating slurry; mix aminated carbon nanotubes and silane coupling agent with the optical fiber coating slurry and disperse them uniformly as an outer coating slurry; wherein, the amino groups will protonate to form -NH3 under acidic or neutral conditions. + This makes the carbon nanotubes positively charged; (2) The preform 7 is drawn into a bare optical fiber 1 in the drawing furnace 6. After cooling, it passes through the first coating cup 2 to coat the surface of the bare optical fiber with the inner coating slurry. After the first layer of two-stage curing 3, it is cured by ultraviolet light or heat to form the inner coating. (3) The optical fiber with the inner coating is prepared by passing through the second-stage coating cup 4. The cup body 8 of the second-stage coating cup 4 is surrounded by a ring coil 9 (see Appendix). Figure 2 As shown), circulating water 10 is used to control the temperature of slurry 11, coating mold 12 is used to control the coating thickness, and current is passed into the ring coil 9 to generate an induced magnetic field. The modified carbon nanotubes in the outer coating slurry 11 are aligned along the optical fiber axis under the action of Coulomb force. After the second layer of two-stage curing 5, UV curing or thermal curing is performed to form the outer coating.

[0025] Specific process parameters and performance characterization parameters are shown in Table 1. The single-mode fiber used has a germanium-doped core with a refractive index of 1.464 and a diameter of 9 μm, and a pure silica cladding with a refractive index of 1.457 and a diameter of 125 μm, corresponding to an NA of 0.14. The multimode fiber used has a graded-variety germanium-doped core with a refractive index of 1.47 and a diameter of 50 μm, and a pure silica cladding with a refractive index of 1.457, corresponding to an NA of 0.20. In this invention, the fiber diameter, inner coating diameter, and outer coating diameter all refer to the outer diameter.

[0026] Table 1

[0027] In Table 1, the tensile strength of each embodiment is greater than 6 GPa, and the m value is also above 50. For the same coating system, as the carbon nanotube doping amount increases, the tensile strength increases, while the m value decreases. The higher the m value, the better the consistency of optical fiber strength. The high-strength optical fiber that this invention aims to obtain has a tensile strength greater than 6 GPa and an m value greater than 50. In the above embodiments, the relevant indicators are all within the range. The corresponding carbon nanotube doping mass fraction of the acrylate coating is between 0.3% and 5%, and for the polyimide coating, this range is 0.5% to 2%.

[0028] Comparative examples are also provided in the specific implementation, as shown in Table 2.

[0029] Table 2

[0030] The comparative data in Table 2 show that for acrylic coatings, if the doping amount exceeds 5%, it leads to excessively high internal stress in the coating, causing brittle fracture, poor fiber strength consistency, and significant fiber attenuation; if the doping amount is less than 0.3%, the strength improvement effect is weak. For polyimide coatings, due to their thinness and high modulus, if the doping amount exceeds 2%, it leads to excessively high internal stress in the coating, causing brittle fracture, poor fiber strength consistency, and significant fiber attenuation; if the doping amount is less than 0.5%, the strength improvement effect is weak.

Claims

1. A high-strength optical fiber, characterized by It includes a glass portion and a coating portion; the glass portion is a single-mode, multimode, or special optical fiber type; the coating portion is made of resin material, specifically including an inner coating and an outer coating; the outer coating is doped with carbon nanotubes at a mass fraction of 0.3% to 5%, and the carbon nanotubes are uniformly distributed along the optical fiber axis in the outer coating.

2. The high-strength optical fiber of claim 1, wherein The diameter of the glass portion is 123μm~127μm.

3. The high-strength optical fiber as described in claim 1, characterized in that... The resin material is acrylate, with an inner coating having a Young's modulus of 0.1~10MPa and an inner coating diameter of 180μm~200μm, and an outer coating having a Young's modulus of 500MPa~1000MPa and an outer coating diameter of 230μm~260μm.

4. The high-strength optical fiber as described in claim 1, characterized in that... The resin material is polyimide, with an inner coating having a Young's modulus of 1 GPa to 2 GPa and an inner coating diameter of 135 μm to 145 μm, and an outer coating having a Young's modulus of 2 GPa to 4 GPa and an outer coating diameter of 150 μm to 160 μm.

5. The high-strength optical fiber as described in claim 1, characterized in that... The aspect ratio of the carbon nanotubes is above 1000:

1.

6. The high-strength optical fiber as described in claim 1, characterized in that... The high-strength optical fiber was tested for tensile strength at a strain rate of 5% / min, and the stress values ​​with a 15% failure probability and a 50% failure probability were both ≥6GPa.

7. The method for preparing the high-strength optical fiber according to claim 1, characterized in that... Includes the following steps: (1) Prepare an acrylate or polyimide optical fiber coating slurry as an inner coating slurry; mix the modified carbon nanotubes with positively charged outer surfaces and silane coupling agent with the optical fiber coating slurry, and disperse them uniformly as an outer coating slurry; (2) The preform is drawn into a bare optical fiber in a drawing furnace. After cooling, it passes through a first-stage coating cup to coat the surface of the bare optical fiber with the inner coating slurry. After UV curing or thermal curing, the inner coating is formed. (3) The optical fiber with the inner coating is passed through the second coating cup. A ring coil is provided around the second coating cup. Current is passed through the coil to generate an induced magnetic field. The modified carbon nanotubes in the outer coating slurry are arranged along the optical fiber axis under the action of Coulomb force. After ultraviolet curing or thermal curing, the outer coating is formed.

8. The method for preparing high-strength optical fiber as described in claim 7, characterized in that... The amino-functionalized carbon nanotubes in step (1) of step (1) are protonated to form -NH3 + to make the carbon nanotubes positively charged.

9. The method for preparing high-strength optical fiber as described in claim 7, characterized in that... In step (1), the optical fiber coating slurry is made of acrylic resin; in step (2), the first-stage coating cup feeding system is controlled within a temperature range of 30℃ to 50℃, and the viscosity of the inner coating slurry is maintained at 1000 to 2000 cps; in step (3), the second-stage coating cup feeding system is controlled within a temperature range of 40 to 60℃, and the viscosity of the outer coating slurry is maintained at 500 to 1000 cps.

10. The method for preparing high-strength optical fiber as described in claim 7, characterized in that... In step (1), the optical fiber coating slurry is made of polyimide resin; in step (2), the first-stage coating cup feeding system is controlled within a temperature range of 20~40℃, and the viscosity of the inner coating slurry is maintained at 1000~2500cps; in step (3), the second-stage coating cup feeding system is controlled within a temperature range of 20~40℃, and the viscosity of the outer coating slurry is maintained at 1000~2500cps.

Images